During FOX Sports Midwest’s always-solid Cardinals Live post-game show following Wednesday night’s loss to Pittsburgh, analyst Rick Horton was asked which minor league players he thought could be called up to St. Louis first.

Horton singled out three likely candidates – outfielder Joe Mather, reliever Chris Perez and outfielder Nick Stavinoha. Each made his major league debut during the 2008 season with the first two having seen enough action to exhaust their rookie eligibility.

All of them make sense. The last cut of the spring, Mather seems logical as the first bat in line to return to the majors. Perez seems a likely call-up to help, especially if the closing situation becomes unsettled. Stavinoha is a bit of a longer shot, but could leapfrog over Mather if he begins the regular season hot.

Still, the name I had most expected to hear was not even mentioned – P.J. Walters. The right-hander has not yet made his first MLB appearance, but seemed to vault to the front of the line as the defacto sixth starter for the Cardinals based on a strong spring during which he allowed just one earned run in nine innings. He then pitched seven strong innings for St. Louis against his Memphis teammates last weekend, with only one unearned run having scored.

Originally scheduled to be Memphis’ opening day starter at home against Oklahoma on Thursday, Walters was pushed back to Saturday to keep him fresh and ready in case he is needed in St. Louis. He would need to be added to the Cardinals’ 40-man roster first, but with just 37 players currently, there is room for Walters if needed.

Mitchell Boggs will be taking the mound instead of P.J. on Thursday night in Memphis, with Adam Ottavino, a mild surprise to have made the club, getting the call on Friday. Ottavino assumes the spot previously held by Jess Todd before the latter was moved to the bullpen. If Walters is not in St. Louis first, he is scheduled to pitch for the Redbirds on Saturday.

I single out Todd since a key reason he was reportedly moved to the pen was to accelerate his ascension to the major leagues. While he may not be quite ready yet, I can easily envision a scenario where Todd falls right in line behind Perez.

Through the first three games of their initial 2009 series, the Cardinals have dodged the rain that would have forced a double-header that almost certainly would have driven a call to Memphis for help. While there is a 70 percent chance of rain on Thursday afternoon increasing to 90 percent that evening, if that game cannot be played, it will likely be rescheduled for later in the season.

So far, the Cardinals starters have not pitched deeply into games, an early indicator of what could be a challenge all season long. The rotation members are averaging fewer than six innings over their first three games. In other words, the bullpen has been asked to pitch over an entire full game’s worth of action already – 29 outs worth to be exact.

If the Cardinals staff doesn’t require reinforcement this coming weekend, at this pace, it still could happen sooner rather than later. After all, the club has just one scheduled day off in their first 34 days of the season.